Savage 223 + CDI BDM and nosedive issue on 8th round

[Kevin1]

The rifle is a Savage 223 in a B&C Medalist stock send to CDI precision to get a BDM.
I’m having some nosedive issue and have no idea on what’s going on.

I have three 10 round mags and all exhibit some sort of nosedive problem.

One MDT, one Accurate Mag that I’ve filed the front polymer to be able to feed longer bullets and one new unmodified accurate mag.

Today I took the new accurate mag to the range for the first time. The round 1 through 7 feed without any problem. But the 8th round would nosedive most of the time. The bullet is the 69gr SMK with a total length of 2.3”

Any idea on what's going on?

 

[Kevin1]

I think I've found the issue.
2 of my mags (MDT and the new accurate mag) seem to have an issue.
I'm able to manually do a nosedive.

On my other accurate mag (front polymer sanded), I simply can't push the front of the round down to have nosedive. When I push the front of round down, I can't push it forward at the same time (I can on the other Accurate mag and MDT). This has nothing to do with the front polymer being sanded, but everything to do with the geometry of the mag (probably the lips are tighter?)Now that I think about it, I don't recall having a nosedive issue with this mag. I didn't have this mag with me last time. I'll confirm next time. But if even by manually forcing I can't cause a nosedive, I'm pretty sure this mag will work fine.